linux-kernel - Re: [PATCH V2 2/2] platform/x86/intel/pmc/mtl: Put devices in D3 during resume

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Message-ID: <e5fce103-fbb6-0eb6-f6ff-4bfeadd89c90@redhat.com>
Date:   Mon, 12 Jun 2023 11:42:45 +0200
From:   Hans de Goede <hdegoede@...hat.com>
To:     "David E. Box" <david.e.box@...ux.intel.com>,
        linux-kernel@...r.kernel.org, platform-driver-x86@...r.kernel.org
Cc:     markgross@...nel.org, irenic.rajneesh@...il.com,
        ilpo.jarvinen@...ux.intel.com, xi.pardee@...el.com,
        rajvi.jingar@...ux.intel.com
Subject: Re: [PATCH V2 2/2] platform/x86/intel/pmc/mtl: Put devices in D3
 during resume

Hi David,

On 6/8/23 01:38, David E. Box wrote:
> An earlier commit placed some driverless devices in D3 during boot so that
> they don't block package cstate entry on Meteor Lake. Also place these
> devices in D3 after resume from suspend.
> 
> Fixes: 336ba968d3e3 ("platform/x86/intel/pmc/mtl: Put GNA/IPU/VPU devices in D3")
> Signed-off-by: David E. Box <david.e.box@...ux.intel.com>

Thank you for your patch.

There is one thing which has me worried here:

What about when real proper drivers show up for these blocks?

I know that at least some people will likely be using the out of tree IPU6 driver with the IPU block.

And having 2 different drivers poke at the hw state seems like a bad idea to me.

Maybe we can add a check if no driver is bound and only set the state to D3 if no driver is bound?

Regards,

Hans



> ---
> 
> V2 - rename mtl_fixup to mtl_d3_fixup. Call it from new mtl_resume
>      function, followed by the common resume. Suggested by Ilpo.
> 
>  drivers/platform/x86/intel/pmc/mtl.c | 29 ++++++++++++++++++++--------
>  1 file changed, 21 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel/pmc/mtl.c b/drivers/platform/x86/intel/pmc/mtl.c
> index e8cc156412ce..2b00ad9da621 100644
> --- a/drivers/platform/x86/intel/pmc/mtl.c
> +++ b/drivers/platform/x86/intel/pmc/mtl.c
> @@ -68,16 +68,29 @@ static void mtl_set_device_d3(unsigned int device)
>  	}
>  }
>  
> -void mtl_core_init(struct pmc_dev *pmcdev)
> +/*
> + * Set power state of select devices that do not have drivers to D3
> + * so that they do not block Package C entry.
> + */
> +static void mtl_d3_fixup(void)
>  {
> -	pmcdev->map = &mtl_reg_map;
> -	pmcdev->core_configure = mtl_core_configure;
> -
> -	/*
> -	 * Set power state of select devices that do not have drivers to D3
> -	 * so that they do not block Package C entry.
> -	 */
>  	mtl_set_device_d3(MTL_GNA_PCI_DEV);
>  	mtl_set_device_d3(MTL_IPU_PCI_DEV);
>  	mtl_set_device_d3(MTL_VPU_PCI_DEV);
>  }
> +
> +static int mtl_resume(struct pmc_dev *pmcdev)
> +{
> +	mtl_d3_fixup();
> +	return pmc_core_resume_common(pmcdev);
> +}
> +
> +void mtl_core_init(struct pmc_dev *pmcdev)
> +{
> +	pmcdev->map = &mtl_reg_map;
> +	pmcdev->core_configure = mtl_core_configure;
> +
> +	mtl_d3_fixup();
> +
> +	pmcdev->resume = mtl_resume;
> +}